Positive type photosensitive image-forming material for an infrared laser and a positive type photosensitive composition for an infrared laser

Abstract

A positive image-forming material for use with infrared laser is provided. The material includes a substrate, a layer (A) containing not less than 50% by weight of a copolymer which contains, as a copolymerization component, not less than 10% by mol of at least one of the following monomers (a-1) to (a-3), wherein (a-1) is a monomer having in the molecule a sulfonamide group wherein at least one hydrogen atom is linked to a nitrogen atom, (a-2) is a monomer having in the molecule an active imino group represented by the following general formula (I): and (a-3) is a monomer selected from acrylamide, methacrylamide, acrylate, methacrylate and hydroxystyrene, which respectively have a phenolic hydroxyl group; and a layer (B) containing not less than 50% by weight of an aqueous alkali solution-soluble resin having a phenolic hydroxyl group. The layer (A) and the layer (B) contain a compound which generates heat upon absorbing light. An image forming material includes the following compounds (II) and (III): R 1 —SO 2 —SO 2 —R 2   (II) R 1 —SO 2 —R 2   (III) wherein R 1 and R 2 may be the same or different, and R 1 and R 2 represent a substituted or non-substituted alkyl, alkenyl or aryl group. The photosensitive image-forming material and positive photosensitive composition have excellent stability of sensitivity with regard to concentration of a developing solution, i.e., have excellent development latitude.

What is claimed is:  
     
       1. A planographic printing plate comprising a substrate and a positive type photosensitive composition for use with an infrared laser, wherein the substrate is a surface-roughened aluminum plate and the positive type photosensitive composition comprises: 
       at least one alkali-soluble resin;  
       a compound generating heat upon absorbing light; and  
       a compound represented by the following formula (III):  
       
         
           R 1 —SO 2 —R 2   (III)  
         
       
        wherein R 1  and R 2  may be the same or different, and R 1  and R 2  each represents a substituted or non-substituted alkyl, alkenyl or aryl group.  
     
     
       2. A planographic printing plate according to  claim 1 , wherein said alkali-soluble resin is one of a resole type phenol resin or novolak type phenol resin. 
     
     
       3. A planographic printing plate according to  claim 1 , wherein a weight-average molecular weight of the alkali-soluble resin is in the range from 500 to 200,000 and a number-average molecular weight of the alkali-soluble resin is in the range from 200 to 60,000. 
     
     
       4. A planographic printing plate according to  claim 1 , wherein said photosensitive composition contains at least one selected from onium salts, quinonediazide compounds, aromatic sulfone compounds and aromatic sulfonate compounds. 
     
     
       5. A planographic printing plate according to  claim 1 , wherein the positive type photosensitive composition further comprises a compound (II), represented by the following formula: 
        R 1 —SO 2 —SO 2 —R 2   (II) 
       wherein R 1  and R 2  may be the same or different, and R 1  and R 2  each represents a substituted or non-substituted alkyl or alkenyl group.